English name: Rasen Sokou no Dystopia
Original name: 螺旋遡行のディストピア 「天然果肉・あずさ ～儚く馴染む汚れの肉棒」 初回限定版
A childhood friend, a girl with large Breasts, uncle pervert, dark summoning and much more wrapped in the story of salvation the next world.
"The main character lived happily with his friends in the end of summer vacation, meets a girl searching for an ancient book. As I understand it, the book needed to prevent the destruction of the world. Where's the hentai learn by watching Rasen Sokou no Dystopia. The hentai is based on the story of the same visual novel."